soil quality and soil health: are they different? and do they matter? susan andrews, national leader...
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Soil Quality and Soil Health: Are they different? and
Do they matter?
Susan Andrews, National LeaderSoil Quality and EcosystemsNational Soil Survey Center
August 9, 2012
Soil Quality Definitions
“fitness for use”- Larson & Pierce, 1991
“capacity of the soil to function”- Karlen et al. 1997
Soil Functions Recognized by USDA-NRCS
Maintaining biodiversity & productivity
Partitioning water and solute flow
Filtering and buffering
Cycling and storing nutrients [and energy]
Structural support and stability
- after Seybold et al., 1997
reflects natural characteristics based on soil forming factors
climate, parent material, topography, and biota, all acting over time – Jenny, 1941
- after Pierce and Larson, 1993
INHERENT SOIL QUALITY
DYNAMIC SOIL QUALITY
Types of Soil Quality
describes status or condition of soil result of land use or management practice
Similar Terms
Genetic v. Kinetic - Richter, 1987
State v. Behavioral Koolen, 1987; Carter et al., 1997
Genoform v. Phenoform Droogers and Bouma, 1997
Both Types of SQ are Important
Soil A Soil B
So
il F
un
ctio
nInherent SQ
Dynamic SQ
50%
85%
Dynamic SQ with respect to Inherent capability
- after Andrews et al., 2004
Soil Health v. Soil Quality
Soil health is used as a synonym for soil quality - Doran and Parkin, 1996
Minor exceptions:
Soil health includes only dynamic quality
Sometimes greater emphasis on biology
A soil may have poor inherent soil quality but still have good soil health.
- Gregorich and Carter, 1997
SQ and SH Use in NRCS
Assessment: Conservation Delivery Streamlining
Soil Survey: Dynamic Soil Properties Inventory
Policy and Programs: EQIP; CSP
Chief’s Initiative: Soil Health Management Systems
It’s not enough for planners to memorize practices, there must be an understanding of principles
Why is soil quality/health important?
Foundation resourceFundamental to sustainabilityValues and Value
Soils are the Foundation Resource
With loss of soil function air and water quality degrade
Soil Quality Air Quality Water Quality
Environmental Quality
Agricultural SustainabilityEnvironmentalQuality
Economic Viability
Social Acceptability
-after Andrews et al., 1998; 2002
Soil Quality as a Component of Sustainability
Soil Quality and Sustainability
Considered an indicator of sustainable land management
– Doran and Zeiss, 2000
Change in SQ with time is the primary indicator of sustainable land management
– Karlen et al., 1997
Value-Laden Term
Human values (and social mores) can’t be ignored
Values are represented in management goal -oriented definition of soil quality
Values may be monetary or non-monetary Farmers define SQ in economic terms Economists use multiple ways to assign value Building quality is linked to several f.b. programs
Principal Threats to Soil Quality: Erosion Organic matter decline Salinization Soil biodiversity loss Compaction Landslides Contamination Sealing - EUC: Thematic Strategy for Soil Protection, 2008
Why do some soils resist degradation better than others?
Components of Functional StabilityComponents of Functional Stability
Soil ResilienceThe ability of a soil to recover its previous level of function after a disturbance
Soil ResistanceThe ability of a soil to resist change in function throughout a disturbance
- Pimm, 1984; Seybold et al., 1999; Andrews, 2003
Differences in Resistance and ResilienceS
oil F
unct
ion
Time (years)CompactionDisturbance
Soil withhigh resistance
Soil with low resistanceand high resilience
-Seybold et al., 1999
Soil with low resistanceand low resilience
Some Factors Affecting Resistance and Resilience
Disturbance Diversity & Complexity Water, Nutrients &
Energy
-after Carter et al., 2003
These factors can be managed!
• Soil Texture• Soil Depth • Soil Horizon
Sequence
These factors are difficult to manage!
(Organic Matter)
Intermediate Disturbance HypothesisD
ivers
ity
Disturbance frequency or intensity
- Connell, 1978 -Neher, 1999, Carter et al., 2003, Andrews, 2003
/
Funct
ion
Intermediate Disturbance HypothesisD
ivers
ity
Disturbance frequency or intensity
- Connell, 1978 -Neher, 1999, Carter et al., 2003, Andrews, 2003
/
Funct
ion
Intermediate Disturbance HypothesisD
ivers
ity
Disturbance frequency or intensity
- Connell, 1978 -Neher, 1999, Carter et al., 2003, Andrews, 2003
/
Funct
ion
There are many paths to the
sustainable land management
What is a disturbance?What is a disturbance?
A natural or human induced stressA natural or human induced stress
Examples for agricultural systems include:
• Heavy traffic load • Tillage• Fertilizers • Pesticides• Monoculture
• Pollutants• Saline irrigation water • Grazing pressure• Weeds• Climate
Rotational Grazing is intermediate disturbance
Reeder (2002) found the highest levels of SOM under intermediately grazed grasslands
Manage for Reduced Disturbance
-after Carter et al., 2003
Types of Disturbance
• Physical
• Biological
• Chemical
Management Strategies
• Minimize tillage
• Increase diversity
• Precision application
Conservation Tillage
So
il F
un
ctio
n
Time
Disturbance
Disturbance
Soil Resilience Decreasing with Time
-Seybold et al., 1999
(with frequent disturbance)
Effect of Improved ManagementEffect of Improved ManagementS
oil
Fu
nct
ion
Time
DisturbanceReduced
Disturbance
-Seybold et al., 1999
Manage for Increased Diversity (biological disturbance)
-after Carter et al., 2003
Some Types of
Diversity & Complexity
• Species & Genetic
• Habitat
• Temporal
• Food Web ‘Health’
• Targeted solutions
Management Examples
• Cover crops, varieties
• Intercrop, trap crops
• Use of Rotations
• Organic amendments
• Limit-specific crops
Cover Crops (PMC SH Study)
The Roller Crimper
Tools to Apply SQ Principles to meet NRCS needs
Simple tools for conservation planning (CDSI)
DSP database and interpretations Identify and quantify soil function Agronomics, forestry, range, economics
Soil Health Management System Initiative
Tools for á la carte Assessment
Visual assessment to determine likely problems
Simple decision tool to aide choice of tests
Needs to be interactive to suggest appropriate tests by region and management system
Observed Concern Related Soil Function SQ Indicator
Ponding Water partitioning Penetration, bulk density
Gully erosion Water partitioning Infiltration, ocular estimate
Poor yield area Productivity Carbon; other limiting factors
Inventory of Dynamic Soil Properties (DSP)
Database of affects of management on function
Focus on reversibility of function loss(Arnold et al.,1990)
Different effects for various soils and climates
Useful to suggest mgt. alternatives and programs
Productivity
Land degradation
103 103
103
103250
Land use impacts
SH Management Systems
Must adhere to principles of IDH by allowing many paths to build soil health
Can encourage innovation to address site-specific issues and management goals
Need a simple tool to mix and match practices
Tool can then point user to management templates or job aids, specific to building SH
Tool to Build a Custom SHMS
Physical Chemical Biological
Tillage and Residue Mgt Integrated Pest Mgt Cover Crops
Controlled Traffic Organic Certification Conservation Rotations
Mulch Application Nutrient Management Alley Cropping
Strip Tillage Precision Application Strip Cropping
Example:
• Choose a minimum of five practices, at least one from each
disturbance category
• Could weight practices by effectiveness and require a minimum score (similar to CMT or SWET)
Practices that Alleviate Physical, Chemical and Biological Disturbance
Summary Soil Health and Quality are synonymous Resistance and resilience dictate the soil’s
function response to disturbance Intermediate levels of disturbance, regardless of
method, relate to higher function For greatest sustainability, manage for:
Reduced physical, chemical & biological disturbance Increases overall function and diversity Increases system stability Optimizes cycling of nutrients, water and energy
“To skin and exhaust the land will result in undermining the days of our children.”
Theodore Roosevelt